I have more than 200 files with Bar charts and Pie charts. Every Time I have to convert the color mode to GrayScale through Menu Bar. (Edit > Edit colors > Convert to GrayScale). After doing that I have to select each and every bar of the chart with Direct selection tool and to round of the Shade Percentage.

For example70.40% to 70% (the value after the dot is below 50)70.60 to 71% (the value after the dot is above 50)